mainboard: Get rid of device_t in ramstage

Use of device_t has been abandoned in ramstage.

Change-Id: I07e00afbbd2c19cf3ea6e08f228eb39e45f1ad0c
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/26983
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/mainboard/emulation/qemu-i440fx/mainboard.c

@@ -26,7 +26,7 @@ static const unsigned char qemu_i440fx_irqs[] = {
 	11, 10, 10, 11,
 };
 
-static void qemu_nb_init(device_t dev)
+static void qemu_nb_init(struct device *dev)
 {
 	/* Map memory at 0xc0000 - 0xfffff */
 	int i;